Learn how complementary TLC-MS and TLC-HPLC-MS methods can be used for successful analysis of neonicotinoid pesticides in honey.

Thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) are known to be convenient, fast and efficient separation techniques enabling analytical methods without the need for
complicated sample preparation or high investments. Low cost and short analysis time per sample is given by parallel analysis of many samples on one plate. The high matrix tolerance of TLC offers additional opportunities to existing routine methods, such as cross-checking of HPLC results or complementary method development.

Various different detection approaches such as analyte visualization by application of derivatization reagents or coupling to other methods like UV detection can be used in combination with TLC. In 1969, Prof. R.E. Kaiser has reported the coupling of TLC with mass spectrometry (MS) for the first time. TLC spots were heated and desorbed into a gas stream in front of the inlet of a mass spectrometer. Numerous publications have demonstrated convincing results and contribute strongly to the progress of TLC, today and in the future.

High-performance liquid chromatography (HPLC) is an established analytical technique for quick and highly efficient analyses of a broad range of complex samples. In contrast to TLC, HPLC can suffer from matrix rich samples causing problems such as increased backpressure or column clogging by accumulation of matrix compounds at the column inlet. In addition, the detection of ghost peaks is possible during repeated sample injections under unsuitable gradient conditions.

The joint use of TLC and HPLC is an option to combine the best out of two chromatographic worlds: High matrix tolerance of TLC makes sample preparation facile or even obsolete and HPLC provides excellent peak capacity for the efficient separation of overlapping TLC bands and increases sensitivity, compared to TLCMS, by band focusing. Combining 2 different phase selectivities can make the TLC-HPLC-MS hyphenation a true 2D-LC method.

In this article we describe the coupling of thin layer chromatography to mass spectrometry (TLC-MS) and the combination of TLC-MS with high performance liquid chromatography (TLC-HPLC-MS) using as an example the detection of neonicotinoid pesticides in honey.

Published  Jul 26, 2019

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